Incandescent electric lamp and method of producing the same



Jan. 24, 1928. 1,657,060

A. BECKET INCANDESCENT ELECTRIC LAMP AND METHOD OF PRODUCING THE SAME Filed Jan. 0, 1925 [MENTOR ATTORNEYS Patented Jan. 24, 1928.

ALAN L. BECKET, OF EAST ORANGE, NEW JERSEY.

INCANDESCENT ELECTRIC LAM]? AND METHOD 0! PRODUCING THE SAME.

Application filed January 30, 1925. Serial No. 5,784.

This invention relates to improvements in incandescent electric lamps and has for objects to provide a construction of this character which has advantageous features with respect to illumination, difiusion of light, anti-glare, longevity, lack of vibration, convenience of packing and shipment, and appearance.

Another object consists in providing certain improvements inthe form, construction and arrangement of the several parts, whereby the above named objects and advantages, as well as others, may effectively be attained.

A further object consists in providing an improved method of assembling the bulb and filament parts of the bulb.

A practical embodiment of the invention is represented in the accompanying drawings, in which a Fig. 1 represents a vertical through the completed lamp.

Fig. 2 represents a detail section, partly in elevation, showing'one of the first steps in assembling the bulb and filament.

Fig. 3 represents a similar view showing a. subsequent step.

Fig. 4 represents a detail section showing a further step.

Fig. 5 represents a detail section taken in the plane of the line VV of Fig. 1, looking in the direction of. the arrows, and showing the final assembly of the filament in the bulb.

Fig. 6 represents a detail section, partly in elevation, showing a modified form; parts bein shown in difierent positions in full section and dotted lines.

Fig. 7 represents a detail section, taken in the plane of the line VII-VII of Fig. 6, looking in the direction of the arrows.

Incandescent electric lamps, as commonly manufactured, have certain disadvantages which. it is highly desirable to overcome. One of these is glare or excessive brilliancy due to the great amount of light concentrated in the small filament. In the efi'ort to reduce this disadvantage, the bulbs have been coated on the outside with more or less opaque material, but this coating very sensibly reduces the light giving power of the lamp. This is probably due to cross reflection between the walls of the coated lamp and also to increased absorption of interheat rays increase the temperature of the filament and thereby tend to accelerate the normal dlsintegration of the filament, for

instance, evaporation of the tungsten material, thereby progressively reducin the efiiciency and life of the filament and, ence, of the lamp.

Another method of reducing glare has consisted in etching or frosting the bulb, but this also results in the disadvantages above named and, when only the lower portion of the bulb is etched, most of the light is obliged to ass through the upper portion of the bul where discoloration or blackenin is. most prevalent. This results in consi erable waste of light due to absorption.

These coated, etched or frosted bulbs also leave somethin to be desired with respect to appearance ecause they are exceedingly prone to an accumulation of dust and dirt.

It might be suggested to lace these coat ings or etchings on the insi. e of the bulb so that they would be protected from dust and dirt, but this presents difficulties inmanufacture. An interior treatment of this kind must be applied to the bulb before the filament is assembled therewith, and such treatment renders the. bulb opaque to such an extent that it is very difiicult, if not impossible, to see and inspect the filament as it is being assembled within the bulb. This is an important disadvantage since the proper 1ocation and assembly of the filament with the bulb is, of course, of the essence of a satisfactory product.

Again, the customary form of bulb allows for a substantial amount of vibration which quite frequently ruptures the filament and, in any event, greatly lessens the efiicienc and shortens the lite of the lamp. Sue vibrations are an extremely serious problem in connection with the illumination of railways and, especially, subways and the like.

In all the usual types of bulb, whether coated or not, the upper portion of the bulb is extremel ineflicient and has a marked tendency to become discolored or blackened through continued use. It is very ineflicient, in so far as proper light giving qualitles are considered.

Again, the extreme concentration of the light in the filament adjacent to or substantially in line with the base of the lamp has a tendency to increase the disadvantage of lare because of the contrast between the hlament and the base, this factor of contrast being very important in the matter of glare.

My structure has been desi ed to overcome these disadvantages, an other disadvantages inherent in the present type of lamp, and to obtain certain other desired features.

Referring to Figs. 1 to 5 inclusive of the drawings, the bulb of the lamp is denoted by 1, and it may be formed of. glass or other suitable material in any well known or approved manner of manufacture.

The main portion of the hulb is preferably formed substantially hemispherical in shape, and its top is depressed so as to form a re-entrant portion within the bulb proper. This top is preferably formed on a parabolic curve, as indicated in Fig. 1, and it may also have corrugations formed therein in any suitable direction, such as circumferential or radial, the latter form being shown in the present instance and marked 2.

These corrugations tend to increase the reflecting capacity of the top and they also enlarge the radiating surface so as to tend to reduce the heat within the lamp.

The outside of the said top is desirably coated with some approved reflecting medium, such as mercury or paint, and it will be observed that such coating is not subject to the disadvanta e resulting from accumulation of dust an dirt, because it is located in a position substantially out of sight.

The arrangement of this top, and its shape, serve to provide a very efficient reflecting surface that pronouncedly diffuses the intense light in the filament and, at the same time, increases the lighting capacity of the lamp. This reflector, instead of focusing the heat rays upon the filament, therefore, has the o posite effect of dispersing them. Again, t is shape of bulb and arrangement of reflector does not generate the cross reflections referred to in connection with the coated or etched bulbs of ordinary construction, and thus does not decrease or absorb the light produced by the filament.

Furthermore, the reflecting surface adjacent the base of the lamp removes the ordinary disadvanta of contrast between base and filament an thereby greatly lessens the contrast factor as promoting lare. The effect of this reflector is that 0 increasing the size of the apparent light source and thus minimizing the glare from the filament.

Finally, the reflector, being formed as a unitarv part of the bulb, is dust-proof on its reflecting surface and therefore eliminates the cost of maintenance necessary with the usual lighting systems in which separate reflectors are employed.

The stem for carrying the filament is marked 3 and it may beof any well known or approved form.

The lead-n wires 4, 5 are made fast in the stem in the usual way, as indicated at 6, 7, and their ends are connected to a filament 8 of tungsten or other suitable material. This arrangement is well understood in the art.

Anchoring members in the form of small wires 9 have their inner ends fixed in the extremity of the stem 3, and their outer ends fast to the filament. These anchoring members are preferably composed of some readily bendable metal, such as is commonly employed for the purpose of supporting filaments in this class of lamps. Their ends are inserted in the stem 3 so that the anchoring members project upwardly at an angle as illustrated in Fig. 2.

When the stem and parts just described have been assembled into a unit, the whole is inserted within the bulbl until the anchoring members and filament have passed entirely through the neck portion 10 thereof. As soon as this position is reached, the slight resiliency of the anchoring members and filament will cause a certain amount of expansion thereof into the position represented in Fig. 3. The operator now pulls upwardly on the stem 3 until it has been elevated, as shown in Fig. 4. This motion causes the contact between the top of the bulb 1 and the anchoring members 9 to spread out the latter into substantially right angular position with respectto the axis of the stem, and thereby distend the filament into practically circular form, as represented in Fig. 5. F01- lowin this, the operator again inserts the stem rther within the bulb and these parts are fused together into the assembly shown in Fig. 1, in a manner well understood in the art. Following this, the usual base is accured to the bulb, in any well known or ap proved manner as, for instance, by a layer of cement 11 located between the threaded metallic sleeve 12, which constitutes the base, and the exterior of the neck 10.

In case the resiliency of the anchoring members is not suflicient to cause the expansion thereof into the position represented in Fig. 3, the result above named may be accomplished by merely movin the stem 3 to one side of the neck of the ulb and then lifting the stem up so as to spread out part of the anchoring members, after which the operation may be repeated with the stem in contact with one or more other parts of the neck of the bulb until all the anchoring members have been spread out as indicated, to the desired position.

In the customary way, also, the lead-in wire 5 is soldered to the sleeve 12, to form one contact; and the lead-in wire 4 is connected to a metallic contact 13 that is set in an insulating button 14, which may be composed of glass or other suitable material, and is carried by the sleeve 12. This construction and operation are also well known in this industry.

The lamp is now complete and may be screwed into a socket and employed in an obvious manner.

The construction of the filament and its supports, and the method of assembling the same with the bulb, enables the provision of a very distended filament in the completed lamp because, after contracting the size of the filament b the angle of the anchoring members, as shown in Fig. 2, the positive contact of the said anchoring members and filament with the top of the bulb in the outward movement of the stem, represented in Figs. 3 and 4:, serves forcibly to expand the filament to the full extent of the anchoring members, an operation which could not take place if reliance were had simply upon the natural resiliency of the filament, such as tungsten. This distended filament not only reatly assists in diffusing the light and reducing glare, but it also increases the distance of the filament from the stem and base thereby reducing the chance of unduly heating the stem and causing the objectionable arcing between the sealed lead-in wires and the further danger of affecting the base cement.

It will be seen that, if desired, the interior of the main portion 1 of the bulb may be coated or etched before the filament is inserted therein and yet the operator will have a full View of the filament while locating it within the bulb because he can clearly see through the top of the bulb owing to its shape and location with respect to the filament. In such cases, the coating of reflecting material, such as mercury, will not be placed on the top of the bulb until after the filament has been inserted.

By coating or etching the lower half of the main portion of the bulb embodying my invention, and leaving the upper half of the main portion clear, a remarkably uniform distribution of light is obtained. The direct rays of the filament are diffused by the coating or etching and practically all of the reflected light will then pass through the clear portion of the bulb which gives a very efiicient and pleasing illumination.

This form of lamp is, as will be seen, very compact and, because of the relatively short axial length, not at all prone to vibrate,

which renders it especially valuable for use in subwaytrains and the like where vibratory forces are almost continuously at work.

Again, the shape of the lamp enables it to be fitted in sockets in such manner as to practically entirely, if not entirely, exclude the base and socket from sight, thereby greatly improving the appearance of lighting fixtures, which is an extremely important commercial consideration. To this end, the top of the bulb is preferably caused to re-enterthe bulb proper a sufficient distance so that the outer rim of the neck portion or outer end of the base, as it may be called, is substantially flush with the top edge of the bulb. However, it may, in certain cases, be desirable to have the base extend slightly above the upper rim of the bulb so as to facilitate the application of the lamp to sockets which do not protrude from their supports. These are commonly called flush sockets.

The compactness of this lamp lends markedly to its shipping qualities because it may be packed in much smaller space than the ordinary lamp and with much less liability of breakage.

Referring to the modified form shown in Figs. 6 and 7, it will be seen that the parts are the same except that the anchoring members for the filament, here marked 15, 16, vary in length so as to give the filament, here marked 17, an angular formation, thereby increasing its length and effective light producing qualities. It will be clear that these forms of filament may be varied to a great extent by simply changing the lengths and arrangement of the anchoring members. In other respects, this modified form in Figs. 6 and 7 is the, same as the preferred form and the method of assembling the parts is also the same. Comparison of the dotted and full line positions shown in Fig. 6 sufliciently indicates the steps followed in assembling the parts, since the same have been fully described in connec tion with the preferred form.

Referring to both forms, it will be seen that the usual tube or duct 18 is fixed in the stem 3 with one end opening into the bulb, as indicated at 19, and the other end opening at the outer end of the stem. This tube is for the purpose of exhausting the air from the bulb when a. vacuum lamp is to be made and for exhausting air and injecting gas .when a gas lamp is to be made. In either case, the outer end of the tube 18 is sealed, in the usual way. when its function has been performed. It may be stated, at this juncture, that my invention has especial features of advantage when employed in the manufacture of gas filled lamps, more particularly with respect to the matter of blackening at certain portions because of convection currents. 1

Again referring to both forms, it should be mentioned that the shape of my improved bulb is such as very largely, if not entirely, to eliminate the blackening which commonly takes place in the upper art of the ordinary bulb due to the partlcles of the fila ment (tungsten) which accumulate there.

In the ordinary bulb, the upper portion is comparatively small and, by virtue of its shape, facilitates the congregation of the tungsten particles into a very objectionable discoloration. In my form of bulb, on the other hand, the upper surface is very large and, by reason of its shape, tends to cause the particles of tungsten to seek the groove at the union of the top and body portion and to congregate there. This groove constitutes,

and may be defined as, a circumspatial cham- The present invention provides a means' of dispersing the convection currents rising from the filament and diverting them away from the base and stem seal; thus reducing the likelihood of over-heating and damaging the said parts. This is accomplished by providing the chamber, which I call a cirand seal.

cumspatial chamber, located at some distance away from and higher than the base The convection currents seek this chamber in accordance with thelaws of convection instead of concentrating around the base andseal as in the ordinary shape of gas filled lamp.

The blackening in gas filled lamps is generally understood to be distributed on the glass by the convection currents which, rising from the hot filament, carry with them particles of tungsten,which particles are deposited wherethe currents first come in contact with the inner surface of the bulb. This is generally near the up er portion of the bulb. I have discovered that the convection currents circulate at a rapid pace around the inside surface of the lamp and that they have a washing or scrubbing eifect thereupon; so that the reason for the accumulation of the blackening in the upper portion of the gas filled lamps is because, at this point, the washing effect of the circulating currents is less powerful than at other places in the lamp. Where the bulb has a sudden change of direction, the currents move somewhat slowly, and are turned in their course in such a way as to counteract each other and to neutralize their force, thereby facilitating the deposit of particles of blackening material at this particular place. On the other hand where the bulb has a wide, free sweep, as in the lower rounded portion, the currents travel at a itlgll rate and their scrubbing action is elfecive. y

The present lamp is so designed as to provlcle a circumspatial chamber in the form of a groove between the upper and lower parts of the bulb, which is calculated to draw the convection currents toward it and.

to thereby relieve the base and stem seal from excessive heat and cause the particles of blackening material to accumulate in the said groove or circumspatial chamber instead of depositing u on the light transmittin portion of the ulb.

urther referring to both forms, it will be understood that various changes may be resorted to in the form, construction, material and arrangement of the several parts and in the steps followed in assembling the parts, without departing from the spirit and scope of m invention, and, hence, I do not intend toe limited to the details herein shown and described, except as they may be included in the claims.

What I claim is:

1. An incandescent electric lamp comprisin a bulb having a substantially hemisp erioal portion and a parabolic portion,

the latter portion being re-entrant within the former, a base on the parabolic portion lyin substantially within the hemispherical portion, and a filament secured to the base and lying below the lowermost part of the parabolic portion, the convex side of the parabolic portion being adjacent the filament.

2. A method of producing an incandescent electric lamp by the use of a bulb with an open base and an expansible filament support, which includes, inserting the filament support throughthe open base within the bulb, and bringing the filament support in contact with the bulb for expanding it.

3. A method of producing an incandescent electric lamp by the use of a bulb with an open base and an expansible filament support, which includes, inserting the filament, support through the open base within the bulb, bringing the filament support in contact with the bulb for expanding 1t, and sealing the filament support within the bulb.

4. A method of producing an incandescent electric lamp by the use of a bulb with an open base and a stem, which includes, inserting filament anchoring members in the stem at an acute angle to its axis, supporting a filament on said anchoring members, inserting the stem and connected parts through the base into the bulb, and moving the stem so as to bring the extremities of said anchoring members in contact with the bulb and thereby bend them into a substantially right angular relationship with respect to the axis of the stem.

5. A method of producing an incandescent electric lamp by the use of a bulb with an open base and a stem, which includes, inserting filament anchoring members in the stem at an ancute angle to its axis, supporting a filament on said anchoring members, in sorting the stem and connected parts through the base into the bulb, moving the stem so as to bring the extremities of said anchor- .ing members in contact with the bulb and thereby bend them into a substantially right angular relationship with respect to the axis of the stem, and sealing the stem Within the bulb.

6. An incandescent gas filled electric lamp, having a circumspatial chamber adapted to collect heat currents given'otl' by the filament.

7. An incandescent gas filled electric lamp, having a circumspatial chamber adapted to collect blackening given off by the filament.

8. An incandescent gas filled electric lamp, having a circumspatial chamber adapted to collect heat currents and blackening-given ofi by the filament.

9. An incandescent gas filled electric lamp comprising, a base, lead-in wires and a coiled filament attached thereto, said lamp having a circumspatial chamber.

10. An incandescent gas filled electric lamp, said lamp having a filament therein and being provided with a chamber surrounding the filament and so formed as to collect the heat currents and blackening given off by the filament.

11. An incandescent gas filled electric lamp so formed as to collect in one portion thereof heat currents and blackening given off by the filament whereby the injurious effect of the blackening on the light transmitting portion of the bulb is retarded.

12. An incandescent gas filled electric lamp comprising, a lower portion, an upper portion, and an intermediate portion, the intermediate portion being so formed as to constitute a rounded groove connecting the upper and lower portions.

In testimony, that l claim the foregoing as my invention, I have signed my name this 27th day of January, 1925.

ALAN lb, BEGKET. 

